In search of a Latin idiom expressing suspicion, i.e., a translation of "I smell a rat" or "something smells fishy"

Question

Is there a Latin idiom, preferably one that was in currency in the classical period, that expresses the speaker's suspicion that something pertinent is being maliciously concealed from him?

For concreteness, in English the idiom might be, "I smell a rat" or "something about this smells fishy".

Probably a direct translation is not going to work; for instance to translate this into French we might say "y avoir anguille sous roche" (literally, "there's an eel under the rock").

I did have a look through Perseus for words like "fishy" and "rat", but it seems that none of the famous translators of Latin literature wanted to use such a base idiom.

Answer 1

sŭbŏleo, -ēre (‘sub’ = a hint, a trace) to catch a whiff, to suspect. Plautus twice: referring to a wife, and later to the man under suspicion.

Possibly the idiomatic answer is to refer to a well known example of suspicion: Hippolytus or Cassandra; or to this or another Fable. http://mythfolklore.net/aesopica/phaedrus/310.htm

Piscosus, fishy, is no use in this case. It means that [the river] is brim full of fish.